Newswise — Washington D.C. – Amino acids are the building blocks for protein in food but also in human muscle. A new study characterizes amino acid intakes among Americans and another new paper examines how intakes correlate with muscle related health outcomes in older adults.
Overall, “the majority of the U.S. population is meeting the minimum dietary recommendations for both total protein and individual amino acids,” the research found. Additionally, within the range of intakes consumed by older Americans, higher essential amino acid consumption does not correlate with higher lean mass or function.
Some dietary recommendations urge older adults to consume more protein, and specific essential amino acids, in order to support muscle mass and strength. This is an important lifestage due to normal age-related declines in muscle mass.
However, associations observed in the National Health and Nutrition Examination Survey (NHANES) do not show muscle-related benefits with greater essential amino acid intake in this population.
The first study found that more than 99% of Americans over age 19 met the Estimated Average Requirements for each of the essential amino acids.
The lack of complete amino acid composition data in food composition databases has made determining population-wide amino acid intake difficult – a gap that is addressed by this new scientific contribution. This cross-sectional study of Americans characterizes intakes of each amino acid and adherence to dietary requirements for each essential amino acid.
According to first author Claire Berryman, PhD, RD with the Pennington Biomedical Research Center at Louisiana State University, “This study was the first to characterize intakes of each amino acid in the US population by gender, age, and race and ethnicity. The analysis allowed us to get a picture of current amino acid intake trends in the U.S. population. Based on our findings, Americans are meeting and exceeding minimum recommendations for all the essential amino acids.”
The second study focused on whether essential amino acid intakes in older adults correlates with lean mass and function, like grip strength. The essential amino acids are so named because the human body requires them but is unable to synthesize them. Hence, it is essential to ingest protein foods that contain them in the diet. The relationships between essential amino acid intake and body composition, muscle strength, and physical function in older U.S. adults have not been well defined until now.
This cross-sectional study evaluated associations between current usual amino acid intakes and body composition, muscle strength, and physical function in U.S. adults 65 years or older.
The study found that amino acids like leucine, lysine and sulfur-containing amino acid intakes were not associated with lean mass, muscle strength, or physical function in adults 65 years or older. However, in an unexpected finding, essential amino acid intakes — particularly lysine — were correlated cross-sectionally with measures of obesity in older U.S. women.
Associations are limited by the fact that intake in a given moment of time does not reflect a lifetime of intake which would be expected to influence body composition. Furthermore, relationships between lean mass and function and essential amino acid intakes higher than the range consumed by the population could not be evaluated.
According to author Claire Berryman, “The findings were surprising to us. We found that eating more essential amino acids in the diet was not associated with lean mass, muscle strength, or physical function in older adults and eating more of some essential amino acids was related to greater fat content in older females. These findings should be interpreted cautiously as they only represent a snapshot in time since we did not follow the participants for any length of time. However, the findings are important and should be explored further given widespread nutritional advice to consume high protein diets and the quantity of high protein foods and supplements on the market. In addition, it is important to keep in mind that consuming any macronutrient — protein, carbohydrate, or fat — in excess of calorie needs will lead to weight gain.”
Both papers were supported by IAFNS’ Protein Committee and appeared in peer-reviewed journals.
The studies are available here and here.
The Institute for the Advancement of Food and Nutrition Sciences (IAFNS) is committed to leading positive change across the food and beverage ecosystem. These papers were supported by IAFNS’ Protein Committee. IAFNS is a 501(c)(3) science-focused nonprofit uniquely positioned to mobilize government, industry and academia to drive, fund and lead actionable research. iafns.org